Here's an idea: Make Zed's abilities deal REDUCED DAMAGE AGAINST MINIONS
Honestly, everyone keeps complaining about Zed being able to win any lane, and having no clear weaknesses, yada yada yada.
The only big thing I have a problem with is his waveclear - for a near 100% pick champion (to say that he's almost solely used to assassinate one key champion and get out quickly, not talking about play-rate) he shouldn't be able to clear entire waves at level 7 with just a WQE, and maybe three auto attacks.
My proposal? Just put a small passive on his Q or E to deal slightly reduced damage on minions so he can't just combo a wave for a few hundred gold.
He should have to work for it, especially since he uses energy, so he can spam his abilities to waveclear if he must. Just a suggestion.